Remove separate .Async namespace
Revert v4.5.1 test projs to v4.5
Convert V45 SqlServer and MySql projs into separate proj dirs which includes all source links
Only include async code in NET45 builds
Add OrmLiteContext for holding async state, store state in CallContext by default
Add V45 Signed projs
Add new OrmLiteV45 test project
Add V45 builds to build.proj